Re: [xsl] Providing a value for the 'select' attribute

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Mark,

On 10/3/2011 5:19 PM, Mark wrote:
> Hi,
> I have been using the following idiom when providing a value for
> bselectb in statements like <xsl:param>, <xsl:variable>, etc., when the
> value provided is not an xsl object. Is this correct or is some other
> form preferred?
>
> <xsl:param name="file-type">
>   <xsl:text>.htm</xsl:text>
> </xsl:param>

This is not incorrect. So it is correct. Some, however (including some 
readers of this list), would argue that it is not optimal.

In essence, absent a specification otherwise (using xsl:param/@as), you 
are declaring the paramater to be a temporary tree (or, in XSLT 1.0, a 
result tree fragment), in this case a root with a single text node child.

If your intention is that $file-type be a string, you should say:

<xsl:param name="file-type" select="'.htm'"/>

or

<xsl:param name="file-type" as="xs:string">.htm</xsl:param>

(which is essentially the same as what you have with as="xs:string" 
added, since the effect of the xsl:text is cosmetic).

Advantages to binding to a string instead of a temporary tree include 
that it will be faster when it is processed as a string (since it won't 
have to be cast to one); and that it will probably behave more as you 
expect it to when under stress ... for example, a string value of "" is 
cast to Boolean false(), while a temporary tree with a single text node 
will cast to Boolean true(), even if that text node has no string value.

Cheers,
Wendell

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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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